This application is based on patent application Ser. No. 11-228930 filed on Aug. 12, 1999 in Japan, the content of which is hereby incorporated by reference.
1. Field of the Invention
This invention relates to a laser irradiation apparatus, in particular, a laser irradiating medical apparatus for treating tumors such as cancer, benign prostatic hyperplasia, etc., by irradiating vital tissues with laser rays, said apparatus being left in vital tissues by means of insertion into vital lumens such as blood vessels, urethras, and abdominal cavities or by means of puncturing organs.
2. Description of the Related Art
A technique of treating lesions by means of laser irradiation apparatuses has been known. The long and slender main body of a laser irradiation apparatus is inserted into a body cavity or a lumen formed by small discission. Lesion tissues are diminished or cleared through alteration, sphacelation, coagulation, cauterization and evaporation by means of irradiating the lesions with laser rays.
The technique is generally to irradiate directly a lesion existing on the surface layer of a vital tissue or its vicinity. However, in order to apply this technique to a deep lesion, heating the lesion to a sufficient temperature, it is necessary to irradiate it with a laser ray of a relatively high power. As a result, there may be a case of or a concern for damaging normal tissues adjacent to the lesion, such as the surface layer.
WO93/04727 discloses a technique for coagulating and diminishing a part of a tumor or prostate by means of laser irradiation. This technique is to infuse a coolant into a balloon in order to heat only the internal tumor or the prostate without heating the surface of the urethra that is adjacent to the balloon. Laser ray is irradiated from a fixed laser irradiator in this case. Consequently, it is necessary to use a low-power laser ray so as not to heat the surface of the urethra, thus requiring a long irradiation time.
U.S. Pat. No. 5,292,320 disclosed an apparatus for treating benign prostatic hyperplasia transurethrally using laser rays. In this apparatus, multiple irradiation units placed at different positions irradiates laser rays simultaneously. The irradiated laser rays are converged on a target point in a deep legion to generate a sufficient heat for heating and diminishing the legion tissue. Consequently, the temperature in the vicinity of the target point becomes higher than other parts where the laser rays do not converge. However, since the light paths of the laser rays are fixed, certain areas are formed where the temperatures are slightly higher than normal in the vicinity of the surface layer where no conversions of laser rays are occurring. This phenomenon provides an ill affect on the protection of the surface. Therefore, it is not satisfactory from the point of treating only a deep lesion while preventing damages on the surface layer.
The object of this invention is to provide an apparatus that effectively irradiates a target area with laser rays, particularly a target area hidden deep inside a vital tissue, while securely preventing damages to normal tissues, particularly, a normal surface tissue that is in contact with the laser irradiation apparatus.
In one aspect of the invention, it is a laser irradiation apparatus, comprising:
a long and slender main body;
a rotating shaft that is held rotatably inside the main body;
an optical fiber provided inside the main body to guide the laser rays;
multiple laser ray emitting parts that are provided on the rotating shaft to reflect the laser rays guided by the optical fiber; and
a drive unit for providing rotation to the rotating shaft, wherein
the multiple emitting parts are arranged on different locations on the rotating shaft along the longitudinal and circumferential directions.
According to the laser irradiation apparatus, it is possible to effectively irradiate the target area hidden deep inside the tissue with laser rays, while preventing easily and securely damages to normal tissues, particularly, the normal tissues which are in contact with the apparatus.
In another aspect of the invention, the laser ray emitting parts are provided to be movable along the longitudinal direction of the rotating shaft and the apparatus further comprises a traveling unit that causes the emitting parts to travel in the longitudinal direction of the rotating shaft.
With such a constitution, it is possible to adjust the depth of a specific area where the laser rays reflected by the emitting part converge.
The objects, features and characteristics of this invention other than those set forth above will become apparent from the description given herein below with reference to preferred embodiments illustrated in the accompanying drawings.